Warp yarn stretching apparatus



Dec. 16, 1969 E. PFARRWALLER 3,4839897 WARP YARN STRETCHING APPARATUS FiledMarch 13, 1968 4 Sheets-Sheet l inveniur: ffW/A/ PFA m? WA 4 4 5 5y J 2 MLVMMW Dec. 16, 1969 E. PFARRWALLER WARP YARN STRETCHING APPARATUS Filed March 15, 1968 4 SheetsSheet 2 in en for EZVW/V PFA EEK/44L EE Dec. 16, M69 E. PF'ARRWALLER WARP YARN STRETCHING APPARATUS 4 Sheets-Sheet 3 Filed March 15, 1968 ml 0 t m V. W

5 M 2 K N. m M 5 Dec. 16, 1969 E. PFARRWALLER WARP YARN STRETCHING APPARATUS 4 Sheets$heet Filed March 15, 1968 5 5 995 mnv am mov A mmwv $031 mcv om ln /gmor;

FEW/IV PFA/FEM/AALEQ nited States Patent 3,483,897 WARP YARN STRETCHING APPARATUS Erwin Pfarrwaller, Winterthur, Switzerland, assignor to Sulzer Brothers Limited, Winterthur, Switzerland, a Swiss company Filed Mar. 13, 1968, Ser. No. 712,698 Claims priority, application Switzerlmd, Mar. 15, 1967, 3,793/67 Int. Cl. D0311 49/22 US. Cl. 13998 5 Claims ABSTRACT OF THE DISCLOSURE There is disclosed, for incorporation into a loom, a device which serves successfully to stretch and then to slacken, cyclically and in opposite phases, the two groups of warp yarns which form the two halves of the shed, i.e. the upper shed and lower shed. The device comprises a rod extending crosswise of the loom at a position between the back rest and the shed, with one group of warps above and the other group below this rod, a crank or cranks fixed at one end to a shaft and coupled at the other end to the rod to raise and lower it upon rocking of the shaft, a crank loosely engaged about the shaft and driven in cyclical rocking motion at one-half the picking rate of the loom, and a pair of collars which are adjustably fixed on the shaft and which possess each a dog against which an abutment the last-named crank engages for a separate sense of rotation of that crank.

The present invention relates to apparatus for cyclically tightening or stretching and slackening the warp yarns in a loom. Apparatus of this kind is used for example to rock the cloth or to compensate for differences in warp yarn length in the open-shed and closedshed positions, in the manufacture of leno-weave cloth. The term rocking denotes a known process in the weaving art which is used in the production of cloths having a high weft density, i.e. having a very large number of intersections between the warp and weft yarns, and preferably for plain weaves.

In rocking, a greater tension is always applied to the warp yarns instantaneously in the bottom shed than to those in the top shed, or vice versa. Consequently, the weft threads, after beating up, are caused on each of a number of successive picks after their insertion and at each warp yarn engaging them to move or creep alternately above and below the center plane or plane of symmetry which bisects the open shed. The function of this rocking movement imposed on the newly picked Wefts is to wrap the warp yarns around these wefts over a large angle, thus insuring that a tight cloth is produced in which the yarn lattice consists of uniformly distributed weft and warp yarns.

Warp stretching and slackening devices have been proposed before. One such known device is driven by a disc cam of the loom dobby, and the warp raising and lowering rod is sought to be driven to one or the other of its yarn stretching positions in as short a time as possible. The ratio of this time interval to the magnitude of the stroke through which the rod is to be moved and hence to the motion of the loom dobby parts which drive that cam cannot be chosen arbitrarily. Consequently, and to an extent increasing with the stretch to be produced by the device, the warp yarns are stretched not only while the shed is closed, as desired, but also While the shed is to a greater or lesser extent open. Increases in warp tension of this kind, especially when they occur in rapid sequence, may readily cause delicate yarns to break. Moreover, the disc cam must be changed to provide any change in the movement of the warp stretcher, such as may be desired to suit different kinds of yarn.

It is an object of the invention to provide a stretching and slackening device which operates to stretch the warps within a part only of the loom operating cycle centered about the closed-shed phase of that cycle, and whose stretching motion is variable with a large degree of independence of the shape or nature of the driving element. In accordance with the invention the tension of the warps to be stretched is increased, one half of the warps at a time, e.g. shortly before or after beating-up but preferably while the shed is closed or nearly closed, so that the warp yarns do not experience additional stressing due to beating-up and to being in the open-shed position.

According to the invention, an input driving element to the thread tightening and slackening device, e.g. a driven crank, is connected to an output driving element thereof, e.g. a shaft, by means of an adjustable coupling, one part of the coupling which is adjustably fixable to the output element having an extension or dog thereon against which an abutment on the input driving element comes to engage within the range of motion of the latter. By input driving element is meant an element closer to the source of power than the output driving element. Conversely, by output driving element is meant an element closer than the input driving element to the ultimate structure which successively and cyclically tightens and slackens the tension on the warp threads.

By means of the invention, an adjustable, selectable portion of the motion of the input driving member may be transmitted to the output driving member with consequent change in the amount of tightening and slackening to which the warp threads are subjected.

With the construction in accordance to the invention therefore, the warp thread stretching and slackening element proper, e.g. a rod passed between the two groups of warps which make up the two halves of the shed, can remain stationary in its central, neutral position for a desirably large portion of the working cycle of the loom. This central, neutral portion is that in which the device has a minimum effect on the warp threads and in particular does not stress one half of them more than the other half. Correspondingly, the time duration of the departure of the warp thread tightening and slackening from that neutral position is very short and this reduces the stressing which the warps experience at the stretching and slackening device during portions of the loom cycle when the shed is not closed. The effective range of operation of the device according to the invention is adjustable. Thus, adjustment may be made of the extent to which the warp threads are deflected from their normal path and thereby supplementarily stressed. Additionally the relation between the two deflections and the neutral positions can be adjusted, so that for example, the deflection imposed on one-half of the warp yarns can be made greater than that imposed on the other half.

In one embodiment of the invention, the phase and stroke adjusting elements are coaxially arranged and take the form of a pair of collars adjustably fixable to a shaft on either side of a crank which is loosely pivoted on the shaft and which is driven at one half the loom cycle or picking rate. The collars have each an abutment or dog against which abutments on the hub of the crank engage for separate senses of rotation of the crank, engagement occurring at phases of the crank motion dependent upon the positions at which the collars are tightened on the shaft. In this way, the times of stretching and slackening can be selected with a relatively large range of freedom. For quite operation, shock absorbent material may be provided to cushion the impact of the abutments on each other.

The invention will now be further described in terms of a number of non-limitative exemplary embodiments and by reference to the accompanying drawings in which:

FIG. 1 is a view in longitudinal section of a loom including a stretching and slackening device according to the invention;

FIG. 2 is a view to an enlarged scale showing a portion of the device of FIG. 1;

FIG. 3 is a horizontal plan sectional view taken along the line III1II of FIG. 1, but shown to an enlarged scale;

FIG. 4 is a perspective view, also to an enlarged scale, of a part of the device of FIG. 1, taken in the direction indicated by the arrow IV in FIG. 3;

FIG. 5 is a perspective view of parts of an alternative form of loom; and

FIG. 6 is a motion diagram useful in explaining the operation of the invention.

Referring to FIG. 1, warp yarns 2 on a warp beam 1 pass over a back rest 3, two guide rollers 4, through the tightening and slackening device of the invention to be described hereinafter, and heddle frames 5 and 6 to a fell 9 disposed at the apex of a shed 7 formed by the frames 5 and 6.

A weft yarn (not shown) is picked into the shed 7 and beaten up by a reed 8 at the fell of the cloth. Cloth 11 which is thus formed passes through temples 13 having covers 12 to a breast beam 14 and thence via a drawing beam 15 and deflecting roller 16 to a cloth beam 17 on which the cloth is wound Guide teeth 18 are affixed to the reed 8 and serve to guide a gripper shuttle (not shown) which picks the weft through the shed.

Droppers 19 of a warp stop motion are disposed between the guide rollers 4. The droppers 19 are placed on the warp yarns 2 and in the event of a yarn breakage initiate a signal to stop the loom. Disposed between the rollers 4 and the heddle frames 5 and 6 are guide rods 28, 28a and 29 which extend transversely of the yarns 2 and whose length corresponds to the cloth width. These rods form a part of the device 10.

Four right-angle members 22 are distributed over the width of the loom (only one of them being shown in FIG. 1) and are secured by bolts 23 to a hollow beam 21 of the loom frame which extends across the width of the loom. Horizontal members 24 are aflixed one to each of the members 22 and have alfixed thereto each two vertical rod holders 25 and a holder 26. These holders extend up between the yarns 2 and are each formed at their free ends with a slot 27 open at the top. The guide rods 28, 28a and 29 are mounted in the slots 27 between displaceable spacers 30, 31, 32 and 33 as further shown in FIG. 2. A plate 34 is affixed to each of the holders 25 and 26 and bridges the slot 27 therein. The plates 34 receive thumb screws 35 and clamp the spacers 32 and 33 against the rods 28, 28a and 29 to secure the latter against motion with respect to their holders. The holders 25 are secured by bolts 36 to the horizontal members 24 at notches 37 in the latter. The holders 26, which are formed with a slot 38, are vertically displaceable on blocks 39 on the members 24. Blocks 39 engage in the slots 38 and are secured to the members 24 by bolts associated with washers 40.

By means of a pin 41, each holder 26 is articulated to a pivot lever 43 which is fastened to a hollow shaft 42 pivotably mounted in vertical arms 22a of the members 22. The arms 22a each carry one half of a bearing, the other half of which is disposed in a bearing cap 60 secured by screws 59 to the arm 22a. Shaft 42 extends over the full width of the cloth and has aflixed thereto four levers 43 each of which is connected to one of the four rod holders 26, as in the construction of FIG. 5.

The shaft 42 has a reduced-diameter end 44 at which it is journaled in a loom frame side upright 61, as can be seen in FIG. 3. Two collars or sleeves 46 and 46' are disposed in laterally inverted relationship on the reduced shaft end 44 as seen in FIG. 4. Each of the collars is split, as indicated at 62 in FIG. 4 for the sleeve 46, and can be clamped to the shaft end 44 by means of screws 45. The hub 48 of a lever 49 fits on the reduced portion 44 of shaft 42 between the two sleeves 46 and 46. The sleeves 46 and 46 and the hub 48 form parts of a dog coupling generally indicated at 47 in FIG. 3. Lever 49 has two cam follower rollers 51 and 52 mounted thereon. They engage two cams 53 and 54 mounted on a shaft 55 (FIG. 1) which is connected to the loom drive via a transmission (not shown), and together compel the lever to fol ow those cams. Hub 48 has two axially extending abutments 56 disposed apart around its periphery and extending over the whole length of that hub.

Each of the sleeves 46 and 46' is provided with a pair of shoulders, 57 on sleeve 46 and 57 on sleeve 46. The shoulders of each of these pairs are likewise 180 apart and extend as dogs axially beyond their sleeves at one end thereof. As is illustrated in FIG. 4, the dogs 57 of the sleeve 46 are engageable each with a separate one of the abutments 56 on the hub 48 for transmission of torque in one sense between the hub 48 and the shaft 44, while the dogs 57 of the sleeve 46' are engageable with the abutments 56 for transmission of torque in the opposite sense between the shaft 44 and hub 48. The sleeves 46 and 46 may be affixed to the shaft 44 by means of the tightening screws 45 (FIG. 4) so as to allow some play of the hub 48 about the shaft between its positions of engagement with the separate sleeves 46 and 46'; Strips of hard rubber, secured by screws 50, may be provided on the dogs 57 and 57 as indicated at 58 to provide cushioning between the abutments 56 and the dogs 57 and 57'.

The warp yarns 2 are threaded between the stationary guide rods 28 and 28a as shown in FIG. 2 but are divided into two groups 2a and 2b of the same or substantially the same number, one of which (2a) passes above the guide rod 29 and the other of which (2b) passes below it. The warp threads 2a which pass above the rod 29 are threaded through heddles of the heddle frame 5. while the warp threads 2b are threaded through heddles of the frame 6.

In operation, the loom drive rotates the shaft 55 and hence the cam pair 53 and 54 at half the speed of the main loom shaft, to one rotation of which there corresponds a working cycle (i.e. one pick) of the loom. During such a cycle a weft yarn is picked through the shed. guided by the reed 8 to the fell 9, and there beaten up after shed change. Cams 53 and 54 impose an oscillating motion on the lever 49, raising that lever to its highest position at one closing of the shed and lowering the lever to its lowest position at the next closing of the shed. The cams are so shaped as to hold the lever 49 stationary in a central or intermediate angular position during a part of the open shed time for which the heddle frames 5 and 6 are farthest apart one from the other. It will be recalled that the guide rod 29 is reciprocated up and down with the rod holders 26 by operation of the levers 43 which are affixed to the shaft 42. The relative circumferential positioning of the sleeves 46 and 46' and levers 43 on the shaft 42 is such that, if no play is provided at the abutments 56, 57 and 57 so that any rotation of hub 48 in either direction imposes as rotation on shaft 42, then for the stationary central position of the lever 49 just described, the guide rod 29 takes up by action of lever 49 a neutral, central position substantially centered between the upper and lower stationary guide rods 28 and 28a. In this neutral, central position of the guide rod 29, the two groups of warp yarns 2m and 2b both contact the guide rod 29 on opposite sides thereof and are both at substantially the same tension.

Since the two groups of warps 2a and 2b together bear the total warp tension which is maintained at the back rest 3, the aggregate tension carried by the warp groups 2a and 2b is constant throughout the weaving cycle. When the heddle frames 5 and 6 are in Wide open shed position, and whichever one is up while the other is down, the guide rod 29 is vertically centered between the stationary rods 28 and 28a to equalize the tension on the two groups of warps. When now the heddle frames move toward closed shed position, the guide rod 29 moves upwardly, or downwardly, as hereinafter more fully explained in connection with FIG. 6, until when the shed closes completely the rod 29 is in its uppermost or lowermost position. FIG. 1 illustrates a phase in the cycle of motion of the warp stretching rod 29 at which that rod has almost reached its maximum height above its centered position and in which the shed has almost closed, frame 6 being in the process of descending with warps 212 while frame 5 is rising with warps 2a. Consequently, the half of the warps 2a which pass above the rod 29 are, in the condition of affairs shown in FIG. 1, subject to a greater tension than the other half 2!) of the warps which pass below rod 29. At the shed change following the state of affairs illustrated in FIG. 1 as just described, when the next loom cycle begins, the guide rod 29 starts to return down toward its neutral, central position, thereby lowering the warp yarns 2a at the location lengthwise of the loom occupied by the device 10 whereas at the location of the shed the warps 2a move above the weaving plane toward top shed position while the yarns 2b move below the weaving plane toward the bottom shed position.

When the shed again closes, with rise of the warps 212 after picking through of the next weft, the guide rod 29 will have moved downwardly to the position indicated at 29 in FIG. 1, below the neutral position therefor above described. Consequently, at this next shed closure the yarns 2b are subjected to greater tension than the yarns 2a. A new cycle of operation then begins with the warp yarns 2a going into the bottom shed while the yarns 2b return to the top shed.

As will be presently seen from FIG. 6, and as indeed is obvious, the time during which the rod 29 is out of its neutral, center position cannot be restricted to the instant at which the shed is closed. Consequently to some degree, and for some times during which the shed is not completely closed, the two halves of the shed will be unequally tensioned.

Basically, it is immaterial whether the guide rod 29 is moved from its central position against the yarns which, at the location of the heddle frames, are in the top shed or in the bottom shed, but it is convenient to move it against the bottom-shed yarns rather than the top-shed yarns, since by moving it against the bottomshed yarns there is produced at the beat-up point 9 a downwardly directed component of force with respect to all warps. As a result, at the point 9 the cloth 11 and the yarns 2a, 2b are always approximately at the height of the breast beam 14 and are not lifted away therefrom.

Referring to the loom shown in FIG. 5, four levers 43 distributed over the width of the loom are secured to a shaft 71 mounted in bearing members (not shown but corresponding, for example, to the angle-members 22 shown in FIG. 1), and in side uprights 81, 82 of a loom frame. The drive for the shaft 71 is disposed on the upright 82. A cam shaft 55 is journaled in upright 82 and has affixed thereto, outside the upright 82, a bevel gear 83 which meshes with a bevel gear 84 mounted on a shaft 85 extending to a loom drive (not shown).

Bolts 73 clamp two sleeves 72 and 72' to the shaft 71. The sleeves 72 and 72' have dogs 74 which engage with matching abutments 75 on a hub 76 of a lever 77, the hub 76 being freely engaged on the shaft 71. The

sleeves 72 and 72 and the hub 76 form parts of a dog coupling generally indicated at 78, similar to the coupling 47 of FIG. 3. Lever 77 is fitted with rollers which are constrained to follow the cams 53 and 54. The other parts of the loom correspond in their arrangement and operation to the loom shown in FIG. 1, except that as compared with FIG. 1, in FIG. 5 the yarn group 2a is shown in the top-shed position and the yarn group 212 in the bottom-shed position. Correspondingly, the guide rod 29 has moved down from its central position to increase the tension of the bottom yarn group 217.

The motion diagram in FIG. 6 shows the motions of the guide rod 29 and heddle frames 5 and 6. The angular positions of the main loom shaft are plotted in degrees along the axis of abscissae. Two loom cycles are shown, i.e. the complete rotation of the machine drive from 0 to 360 is shown twice. The cam shaft 55 makes one complete revolution during two main shaft revolutions. Curves A, E, S T are plotted along the ordinate. The heavy solid-line curve A represents the movement of the guide rod 29 for an adjustment of the sleeves 46 and 46' of the coupling 47 without play therein, i.e. such that their pairs of dogs 57 and 57 contact the abutments 56 of the hub 48 simultaneously on both sides, the clearance shown at 63 in FIG. 4 being absent. With such an adjustment of the coupling, the movement of the rod 29 is controlled exactly in accordance with the shape of the cam pair 53, 54.

In contrast, the dash-line curve B represents the movement of the rod 29 for an adjustment of the coupling 47 in accordance with FIG. 4. The sleeves 46 and 46' are so adjusted that, with the roller lever 49 in its neutral, central position and with the rod 29 in its neutral position also, there are equal clearances 63 between each of the abutments 56 and the dogs 57 and 57 with which that abutment 56 is engageable. Consequently, the coupling 47 transmits to the rod 49 only part of each rocking movement of the lever 49.

The solid-line curve S represents the movement of the heddle frame 6 controlling warps 2b and the dashline curve T represents the movement of the heddle frame 5 controlling warps 2a. At the angular positions 0 and 360 (F, F, F) of the main loom shaft, the frames 5 and 6 and hence the yarn groups 2a and 2b are, at the shed, in the closed-shed position. During the first cycle, the frame 6 driving the yarn group 211 moves into the top shed as shown at curve S while the frame 5 driving the yarn group 2a moves into the bottom shed as indicated at curve T Both then move back into the closed-shed position at the end of the first loom cycle denoted by point P.

During the second cycle, frame 6 moves into the bottom shed and frame 5 into the top shed. Beating-up occurs at the 50 position, and picking into the open shed starts at the position.

In accordance with the curve A, the guide rod 29 is in its bottom position h at the phase F of the first cycle, providing at the location of the stretcher 10 a maximum deflection or deviation L to the warp threads 2b for the instant during which the shed is fully closed. After the shed change at F, the lever 49 pivots the shaft 42 clockwise, as seen in FIG. 1, so that the guide rod 29 rises towards its neutral, central position, reaching it at the angular position or phase H in FIG. 6. As rod 29 rises, the yarn group 2b rises with it due to its own tension and returns towards the plane of weaving. With the shed open, the guide rod 29 dwells from phase H to phase D in its centered, neutral position approximately at the level of the plane of weaving until at the angular position D in FIG. 6, the cam pair 53, 54 start to pivot the lever 49 further clockwise. Since the coupling 47 has been adjusted without play between the sleeves 46 and 46 and the hub 48, the guide rod 29 is at once raised, and with it the yarns 2a, until rod 29 reaches its top position 11' and its maximum upward deflection L at the angular position F, by which time the shed has closed again. The angular position C corresponds approximately to the instant of time at which frames 5 and 6 and the rod 29 take up the positions shown for them in FIG. 1. Thus, in FIG. 1, the shed is closing and rod 29 is rising, having almost reached its highest point of travel.

At phase F of the main loom shaft the cam shaft 55 has rotated through 180 from the position which it occupied at the main loom shaft phase denoted F, and the second loom cycle starts. After shed-change at phase F, the lever 49 and shaft 42 pivot back anti-clockwise (as seen in FIG. 1) so that the guide rod 29 descends. Because of their tension, the yarns 2a which had been deflected upwards by the rod 29 return towards the plane of weaving. At angular position H rod 29 regains its neutral, central position and remains therein for a period of time measured by the separation of points H and D and which is dependent upon the shape of the cams 53 and 54. This period occurs during the new opening of the shed, warps 2a being now in the top shed and warps 2b being in the bottom shed.

At the angular position D the lever 49 resumes its anti-clockwise rotation. The guide rod 29 moves below its center position, pressirn against the yarn group 2b below it and descends until it reaches its bottom position h" of maximum deflection L at the angular position F, at which time frames 5 and 6 reach closed shed position. The deflections L, L, L are identical. At position F" the cam shaft 55 has rotated through 360 from the phase F. A fresh cycle starts, in the manner hereinbefore described, with shed-changing at the position F".

When play circumferentially of the shaft 44 is provided between the sleeves 46 and 46 and the hub 48, the motion of the rod 29 out from its center position starts later, and its return thereto occurs earlier than in the case of the rigidly coupled, play-free drive represented by the curve A. This is indicated by curve B in FIG. 6. The lever 49 moves during the time intervals F-H, DH and DH" in FIG. 6, and when no play is provided, the lever 43 moves during those same time intervals. When instead some play is introduced, the lever 43 moves over shorter time intervals represented in FIG. 6 at FG, EG and E-G. When no play is provided, lever 43 and rod 29 are held in their neutral position of no deflection over the time intervals H-D and H'D by positive drive from lever 49 via shaft 44. When in contrast play is provided, the lever 43 and rod 29 are held in their neutral position of no deflection over time intervals G-E and GE simply by the tension of the warps.

Since when play is provided the coupling 47 transmits to the guide rod 29 only part of the rotation of the lever 49, the deflections K, K and K or rod 29 are correspondingly less than the deflections L, L and L" occurring when no play is provided. At the angular position F the rod 29 is in its bottom position in corresponding approximately to the dash-line position 29' in FIG. 1. After the shed-change at F the lever 49 pivots clockwise. The tension of the yarns 2b raises the guide rod 29, thereby holding the hub 48 in engagement with the sleeve 46 until rod 29 reaches its center, neutral position, which it does at phase G in FIG. 6. Rod 29 is retained in that position by the yarns 2a and 2b whereas lever 49 continues to rotate until phase H is reached, engagement between abutments 56 and the dogs 57 of sleeve 46 disappearing at phase G. After reaching its central position at phase H, lever 49 remains there until phase D.

The lever 49 starts to pivot clockwise again at phase D. The adjustment of the sleeves 46, 46 is such that phase B is reached before abutments 56 engage the dogs 57 on sleeve 46. Beginning at phase E, shaft 42 is compelled to rotate clockwise and the rod 29 is raised correspondingly until it reaches substantially the solid-line position shown for it at 29 in FIG. 1 at phase C and its highest position denoted in in FIG. 6 at phase P, where the shed is completely closed.

During the next loom cycle the lever 49 pivots back anti-clockwise, beginning at phase F. The weight of rod 29 and the tension of the yarns 2a preserve engagement between the dogs 57 of sleeve 46 and the hub 48. Rod 2'9 is lowered correspondingly and at angular phase G reaches its neutral, central position, to be retained therein by the yarns 2a and 2b. Abutments 56 on hub 48 therefore disengages from dogs 57 and lever 49 continues to rotate counterclockwise until it reaches its neutral, center position at phase H, remaining there until phase D.

At D lever 49 resumes its motion anti-clockwise. Because of the backlash or play 63, phase E is reached before abutments 56 engage the dogs 57 of sleeve 46. Upon such engagement shaft 42 is forced to rotate counterclockwise and rod 29 sinks correspondingly until it reaches its bottom phase m at phase F. The deflections K, K. K are identical to one another. A fresh cycle starts with the shed-change at phase F.

The sleeves 46 and 46 can be so adjusted that, when the lever 49 is in its central position, there are different backlashes 63 between the separate abutments 56 and the two dogs in each of the pairs 57 and 57. In this way it is possible, for example, to make the deflection of the rod 29 above its neutral position greater than its deflection below that neutral position or vice versa. If it is desired to effect periodic stretching of only one yarn group such as the group 212, it is sufficient to provide a single sleeve, ie the sleeve 46'. The other sleeve 46 can either be completely omitted or can be turned on shaft 42 so that its dogs 57 are outside the range of movement of the abutments 56.

The invention thus provides apparatus for tightening and slackening warp yarns in a loom. The apparatus cornprises a longitudinal member (the rod 29 in the embodiments described) which extends crosswise of the loom. The apparatus further comprises an input driving member (the lever 49 with its annular hub 48, in the embodiment of FIGS. 1 to 4) coupled to the loom drive to execute a cyclical motion at half the picking rate. The apparatus further comprises an output driving member (the shaft 42 in the embodiment of FIGS. 1 to 4) which is coupled to the longitudinal member (by levers 43 and holders 26 in the embodiments described). The apparatus also comprises an adjustable lost motion coupling between the input and output driving members. This coupling includes at least one abutment on the input driving member, at least one abutment effectively on the output driving member and means adjustably to aflix at least one abutment on one of those driving members within the range of motion of an abutment on the other of those driving members. In the embodiment of FIGS. 1 to 4. reference character 56 identifies abutments on the input driving member 49, while reference characters 57 and 57' identify abutments effectively on the output driving shaft 42, and the collar 46 or 46, or both, constitute means adjnstably to afiix an abutment or abutments effectively on the output driving shaft 42 within the range of motion of the abutments 56 on the input driving member While the invention has been described hereinabove in terms of a number of presently preferred embodiments. the invention itself is not limited thereto but rather comprehends all modifications on and departures from the embodiments so described and illustrated, properly falling within the spirit and scope of the appended claims.

I claim:

1. Apparatus for tightening and slackening warp yarns in a loom, said apparatus comprising a longitudinal member extending crosswise of the loom, an input driving member coupled to the loom drive to execute a cyclical motion, an output driving member coupled to said longitudinal member, and an adjustable lost motion coupling between said input and output driving members, said coupling including at least one abutment on each of said input and output driving members, and means :adfustably to affix at least one of said abutments on one of said driving members within the range of motion of one of said abutments on the other of said driving members.

2. Apparatus according to claim 1 wherein said output driving member comprises a shaft, wherein said input driving member comprises an annular member engaged on said shaft for rotation with respect thereto, and wherein said coupling comprises a sleeve engaged on said shaft and adjustably fixable thereon, said annular member and sleeve each carrying at least one of said abutments.

3. Apparatus according to claim 1 wherein said coupling includes shock absorbing means engageable between said abutments.

4. Apparatus according to claim 2 wherein said means adjustably to affix at least one of said abutments on one of said driving members includes releasable means to tighten said sleeve about said shaft.

5. Apparatus according to claim 1 wherein said input driving member is coupled to the loom drive to execute a cyclical motion at half the picking rate of the loom.

References Cited UNITED STATES PATENTS 2,090,785 8/1937 Diederichs 139-115 X 2,556,055 6/1951 Bahan 139-97 2,649,864 8/1953 Mayer et a1. 13997 3,125,128 3/1964 Pfarrwaller 139l15 OTHER REFERENCES Improve Your Fabics-With the SRRL Loom Attachment, reprinted from Textile World, July, 1952.

JAMES KEE CHI, Primary Examiner PO-HJSO UNITED STATES PATEN L 0% F ICE CERTIFICATE OF CORRECTION I K). On 3 1-1 mm i P t t N J J 3 z f Dated JCCLhibQJ. lgfi Inventor(s) lira-iii: ijtiarrweller It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Edward M. Fletcher, Jr.

Attesting Officer 101.1111) 3 line ill l, for "successfully --nucceuslvuly-e.

Golmm I", Tlg'me (S3, for "quite" substi tujtcz ;nf (:t--.

601mm; if, line 32:, for "wound Guide" substitute -1 O111'1:1. GUl L( (101mm: 1-, line 3, -.'.L1'1sert --:[rec1y-- after "fits" 601mm 10, line 10, for "I Jyer e1; Ell. suimtitmze --I--f0,; ?r, Jr. an; al.--.

SIGNED AN'D SEALED JUN9 197 Q Attest:

mm: I. am, JR. Commissioner of Patents- 

